How to Build a Scalable Web Search Engine

🔍Building a web search engine requires handling user queries, finding relevant sites, and displaying results with titles and descriptions.

📚The search engine needs a database containing every webpage on the internet, which is obtained through crawling and storing site content.

🗄️To efficiently store the large amount of webpage content, a blob store like Amazon's S3 can be used, while metadata is stored in a database.

🔢The database is sharded and distributed to handle the vast amount of data, using shard keys like URL, hash, and word frequency.

🕷️Crawlers fetch webpages, extract URLs, and store the content in the database, respecting the robots.txt file to avoid unnecessary requests.

How does a web search engine find relevant sites?

—The search engine uses a database containing every webpage on the internet, obtained through a web crawler that finds and stores site content.

How is webpage content stored?

—Webpage content is stored in a separate blob store, like Amazon's S3, for efficient storage, while metadata is stored in a database.

How is the large amount of data managed?

—The database is sharded and distributed across multiple nodes, allowing for efficient storage and retrieval of data.

What is the role of the web crawler?

—The web crawler fetches webpages, extracts URLs, and stores the content in the database, while respecting the robots.txt file to avoid unnecessary requests.

How does the system handle scalability and caching?

—The system can scale by adding more crawlers and distributing them geographically. Caching is used to store robots.txt files for efficient crawling.

00:00This video teaches how to build a scalable web search engine, similar to Google.

00:27A web search engine requires handling user queries, finding relevant sites, and displaying titles and descriptions.

01:15The search engine needs a database of every webpage on the internet, obtained through crawling and storing site content.

03:33Webpage content is stored in a blob store, while metadata is stored in a database for efficient storage and retrieval.

05:11The database is sharded and distributed to handle the vast amount of data.

07:47Crawlers fetch webpages, extract URLs, and store content in the database, respecting the robots.txt file for efficient crawling.